TWI466859B - Process for treatment of phenol and tar acids containing oil - Google Patents

Description

Method for treating oil containing phenol and tar acid

The present invention relates to a novel method for treating oils comprising phenol and taric acid, which is extracted (or recovered) by recovering (or recovering) phenol and tar acid by liquid phase-liquid phase extraction and distillation, and then borrowing Further post-treatment is carried out by the combination of crystallization and distillation.

A phenolic mixture oil, i.e., a phenol and a derivative thereof (cresol, xylenol), hereinafter referred to as phenol and tar acid, can be obtained by treatment with various methods such as coal, petroleum or biomass. The oil or mixture thereof comprising phenol and tar acid by treating coal, petroleum or biomass is used as feedstock oils.

Since the distillation range of phenol and tar acid is similar and the boiling point range of the fraction is narrow, it is extremely challenging to extract these compounds from these oils. Therefore, general direct distillation is not considered to be an appropriate method for obtaining phenol and tar acid, and thus, in the past studies, the use of a liquid-liquid phase extraction system has been attracting attention.

The prior art utilizes caustic soda to promote the extraction of phenol and tar acid in the oil raw materials. When these oils are mainly alkaline or neutral, the acidic nature of the phenol and tar acid can be extracted by the diluted alkaline solution. For this purpose, caustic is used as a solvent for the manufacture of sodium phenolate, which is then acidified with a mineral acid, usually sulfuric acid. The advantage of this method is that it can highly extract all the organic acids in the oil by enhancing the transfer of sodium; and the inherent disadvantage of this method is mainly the production of a large amount of aqueous waste liquid. The neutralized aqueous solution contains high salts and is therefore difficult to reuse, so this method produces a large amount of aqueous waste liquid. To avoid this problem, other neutralizing agents have been used, such as exhaust gases containing high amounts of carbon dioxide which have been used to acidify phenol mixtures. Although this solution can effectively reduce the generation of waste liquid, it will cause solid carbonate recovery problems during the neutralization process. After this solid state is recovered, it is decomposed in the boiler to produce lime, which is then used to make the phenol aqueous solution caustic. Due to the considerable energy consumption of the boiler, the final efficiency of the process is thus reduced.

Alternative methods that have been developed include the liquid phase-liquid phase extraction with water as a solvent (see U.S. Patent 2,888,491), the extraction of phenol and tar acid at high temperature (about 160 ° C) high pressure (about 20 barg), followed by two Dilutions up to six times the extract volume were extensively diluted. This dilution is necessary in order to extract excess oil dissolved in the extract; and this dilution is also necessary in order to ensure acceptable performance upon post-treatment of the diluted extract. However, this represents a significant increase in the volume of phenol and taric acid that requires further processing, resulting in a reduction in process efficiency. The final purification is the use of butyl acetate for additional liquid-liquid phase extraction, followed by recovery of butyl acetate and concentrated phenolic mixture to complete the process. Several other solvents have also been used to extract phenol from aqueous solutions, as many organics can achieve the same goal: high non-water miscibility, phenol and tar acid tend to be distributed in the solvent. Examples of commercially available ketones (e.g., methyl isobutyl ketone) or ether have been reported to treat, for example, high phenol wastewater.

Other methods for extracting phenol and tar acid from oils include advanced liquid-liquid phase extraction using both solvent, counter solvent and sometimes additional diluent (see U.S. Patent 5,964,987; U.S. Patent 2,666,796; U.S. Patent 2,766,296; U.S. Patent 2004/0200717). Most of the solvents used are ethylene glycols (see U.S. Patent No. 5,964,987; U.S. Patent No. 2,790,834; U.S. Patent No. 2004/0200717), such as ethylene glycol or triethylene glycol, which are used alone or in the form of an aqueous solution. . These solvents have a number of disadvantages, such as their low selectivity to phenols and other oily compounds, and the extract must extract a large amount of oil dissolved in the extraction solution by vapor stripping. Another disadvantage is that these solvents are relatively sensitive to temperature: these solvents are cleaved during the heating process of distillation in the atmosphere, and in order to recover these solvents, this step must be carried out by vacuum distillation, but the risk of cracking cannot be completely avoided. Therefore, in order to compensate for the loss of cracking, some of the solvent must be taken out and replaced.

Other commonly used solvents are alcoholic compounds such as methanol (see U.S. Patent 2,666,796; U.S. Patent 2,766,296). Due to the volatility of methanol, it is necessary to compensate for the loss with a new solvent. In addition, when methanol is used as an aqueous mixture, it is necessary to mix methanol and water before the solvent is recovered and before entering the recovery loop. This means that additional steps need to be taken immediately after the methanol recovery, such as: to avoid ethylene glycol.

Commonly used counter solvents are paraffinic hydrocarbons such as n-hexane or naphtha (see U.S. Patent 5,964,987; U.S. Patent 2,666,796; U.S. Patent 2,766,296; U.S. Patent 2004/0200717). The purpose of using the counter solvent is to make the extraction easier. The oil to be treated must be soluble in the counter solvent, so that it can be changed by changing the interaction between the mixed oil + strip solvent mixture and the extraction solvent. The efficiency of phase-liquid phase extraction. In the absence of this counter solvent, the efficiency of the liquid-liquid phase extraction process is greatly reduced. However, this method also indicates that an additional recovery loop is necessary to recover the counter solvent. Since the stripping solvent is generally similar in nature to the oil compound having a lower boiling point, the extraction may not be easy and there is a possibility of loss of the counter solvent, and the oil obtained by extracting the phenol and tar acid is very It may cause different degrees of contamination depending on the recovery efficiency of the counter solvent. In the case where the nature of the stripping solvent is quite different from that of the oil compound, its commercial value is reduced by contaminants, which is especially true for high aromatic content materials such as coal tar, since paraffin is not the main compound in the raw material. .

The importance of the aforementioned systems on an industrial scale has been confirmed in the literature, however they are still quite complex and heavy in the use and recycling of solvents. In some cases it is necessary to strip the extract with steam and/or additional distillation, resulting in high energy consumption. These methods are described, inter alia, in the treatment of concentrated feedstocks such as oil feedstocks containing about 30% phenol and are used to treat high flow feedstocks. Combined with these points, although the method shows better investment compensation and operating expenses for specific content and high phenol-containing oil products, it is not necessarily competitive for oils containing low phenol and tar acid and small-flow oils.

The object of the present invention is to reduce the above disadvantages, and to propose a novel liquid-liquid phase extraction and distillation arrangement, after which a crystallization step can be carried out to obtain a mixture of pure phenol and tar acid, combined with crystallization and distillation steps, from phenol and An additional purified tar acid is produced in the taronic acid oil.

This process is therefore suitable for the extraction of oils containing phenol and tar acid from different raw materials. To obtain these raw materials, tar obtained by, for example, pyrolysis products such as coke production or gasification steps can be obtained. Other materials such as gasification or pyrolysis of biomass may also be used, such as oils obtained by pyrolysis of lignocellulosic materials such as palm kernels.

The process is reduced to three to four main units, and the implementation steps of each unit are as follows:

- The acid in the feedstock is transferred to the solvent with water as the first extraction reagent. This process can be carried out, for example, in a solvent extraction column, but is not necessarily limited to such a device.

- thoroughly mixing the large amount of the extract obtained in the first step with a non-water-miscible solvent which is a single or polycyclic aromatic hydrocarbon, with or without a substituent, or a compound as described above mixture. The non-water-miscible solvent, preferably a single or polycyclic hydrocarbon, is substituted with at least one alkyl group, and more preferably one methyl group and/or one ethyl group. For example, the non-water-miscible solvent can be selected from (but not limited to) benzene, toluene, o-xylene, m-xylene, p-xylene, 1,3,5-trimethylbenzene, ethylbenzene, 1- Methyl ethylbenzene, 1-ethyl-2 toluene, 1-ethyl-3-tolyl naphthalene, 1,2-dimethyl-3 ethylbenzene, 1,2-dimethyl-4-ethylbenzene, 1,2 - dimethyl-5 ethylbenzene, 1,3-dimethyl-2 ethylbenzene, 1,3-dimethyl-4 ethylbenzene, 1,3-dimethyl-5ethylbenzene, 1,4-two Methyl-2-ethylbenzene, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1-ethylnaphthalene, 2-ethylnaphthalene, 1,2-dimethylnaphthalene, 1,6-dimethylnaphthalene , diphenyl, 2,6-dimethylnaphthalene, anthracene, fluoranthene, phenanthrene, or a mixture of the foregoing compounds and various other traces of hydrocarbons, notably including toluene, benzene, benzene-toluene-xylene mixture ( BTX) or a fraction or mixture of industrial wash oils.

- In the third step, the second solvent is separated from the extracted phenol and tar acid by distillation to obtain a mixture of concentrated phenol and tar acid, and a purified solvent is obtained above the column.

- Finally, the mixture obtained by distillation is separated by crystallization to obtain a mixture of taric acid and pure phenol. The recovery of pure phenol and tar acid compounds from crystallization is more efficient than previous accurate fractional distillation methods.

In a preferred embodiment, the final crystallization step is not included. In general, when the phenol and taric acid oil to be treated are in a small amount or in a medium amount, the concentrated phenol and tar acid may be used directly or further processed by the user.

In a preferred embodiment, the crystallization step is a combination of crystallization and distillation to additionally purify pure oleic acid.

The present invention presents the following advantages and advances:

- No need to use any alkali or acid, alkali or acid usually produces a large amount of waste material to be treated.

- Competitive treatment of oils containing low initial amounts of phenol and tar acid.

- Competitive for handling low oil rates.

- The solvent used can selectively remove phenol with limited or negligible oil absorption.

- The solvent used is not temperature sensitive and can be recycled under its optimum conditions, and its replenishment and loss can be ensured to a limited extent.

- The solvent used is selected according to the composition of the raw materials, and because of its non-polluting nature, the commercial value of the treated oil is not reduced.

- No formation of solid contaminants such as sodium carbonate or sodium sulfate.

The present invention exhibits the following unique characteristics:

- two liquid-liquid phase extraction systems in series

- using water as the first solvent

- a single or polycyclic, substituted or unsubstituted aromatic hydrocarbon, or a mixture thereof as a second solvent.

- The stripped oil is not recovered by stripping.

- Final purification by crystallization and/or distillation.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a treatment apparatus for producing a mixture of pure phenol and tar acid from an oil containing phenol and tar acid according to the present invention. Fig. 1 shows an oil raw material containing phenol and tar acid from a stream 1, and an optimum temperature for extracting phenol and tar acid by heat exchanger 2. The target temperature is set between 60 and 160 ° C and the pressure is higher than the vapor pressure of the resulting mixture. The raw materials are introduced into the liquid-liquid phase extraction unit 4 and treated with water, which is fed from stream 3 and recovered from stream 9 (described later) and replenished by stream 22. The extraction is carried out in an extraction unit 4 to produce a treated oil stream 6 and an aqueous solution 5 containing phenol and tar acid. The treated oil 6 is substantially free of phenol, and depending on its composition, stream 6 can be further purified, for example by distillation or by crystallization of its melt.

The solution 5 containing phenol and taric acid is introduced into a liquid-liquid phase extraction apparatus 8 containing a single or polycyclic, substituted or unsubstituted aromatic hydrocarbon or a mixture thereof as a solvent. The hydrocarbon solvent is then passed from stream 7 to liquid phase-liquid phase extraction unit 8, which is recovered from stream 17 (described later) and hydrocarbon solvent is supplemented by stream 23. After the extraction device 8 completes the extraction, two streams are formed: a water stream 9 and an organic solution 10 of phenol and tar acid. The water stream 9 is substantially free of phenol and tar acid, and there is also the possibility of causing the stream 9 to discharge a portion of the water by discharging the stream 24.

The organic solution 10 of phenol and tar acid is heated to the desired temperature by the preheating unit 11, and the preheating unit 11 must set the injection stream 12 of the distillation 13 at the desired temperature to control the distillation. The heating medium used in the preheating device 11 can be a special purpose stream (not shown), or a framework optimized for heating management of the plant with additional heat exchange means or economizers. The design is so that the preheating device 11 represents a function rather than a single instrument.

The preheated phenol and taric acid organic solution 10 enters the distillation system 13, and the distillation system 13 is a recovery system that allows the hydrocarbon solvent to be recovered as an overhead product, which allows the hydrocarbon to be optimally recovered. Go on.

The recovered hydrocarbon solvent becomes stream 15 and condenses in heat exchanger 16. The cooling medium used in the condenser 16 can be a special purpose stream (not shown), or designed with an additional heat exchange device or e.g., an economizer, optimized for heating management of the equipment, so the condenser 16 represents a function rather than a single instrument. The condensed and cooled hydrocarbons are recovered as stream 17 and recycled to stream 7 for reuse. There is also the possibility of discharging a portion of the hydrocarbon solvent from stream 17 by stream 25.

The concentrated phenol and tar acid mixture is recovered in streamer 14 as stream 14 and introduced into heat exchanger 18. The purpose of the heat exchanger 18 is to allow the phenol and taric acid mixture concentrated by the distillation apparatus 13 to be cooled before entering the crystallization unit 19. The cooling medium used in the cooling unit 18 can be a special purpose stream (not shown) or designed with an additional heat exchange unit or an economizer in the framework optimized for equipment heating management, so that the condenser 16 It is a function rather than a single instrument.

Zone 19 is the final purification stage for the production of phenol and tar acid. Zone 19 consists of one or more crystallization units combined with a distillation apparatus, the detailed nature and arrangement of which is determined by the functionality required for the selected purification strategy. This purification policy is determined by the initial allocation of initial injection 1, which will result in a mixture of phenol and tar acid, or a mixture of phenol and tar acid plus a portion of pure tar acid. Zone 19 can be used to extract phenols with a purity greater than 95%, or better, pure phenols with a purity greater than 99%. Expressed by streams 20 and 21, this particular example produces a pure phenol stream 20 and a tar acid mixture 21.

[Examples]

The following examples use the equipment previously described to extract phenol and tar acid from an oil feed of 1500 kilograms per hour. The preferred embodiment lacks the final crystallization unit as shown in Figure 1.

The oil raw material 1 containing 10 to 20% of the phenol and taric acid injection is injected into the heat exchanger 2, and the oil/water distribution coefficient of the phenol and the tar acid is preferably at a higher temperature. As described earlier, the temperature of the heat exchanger 2 is adjusted so that the column temperature is 60 to 160 ° C, and in this example, the temperature is preferably 90 ° C. The stream discharged from the heat exchanger 2 is introduced into the liquid-liquid phase extraction unit 4 in countercurrent contact with water. In this example, the extraction device 4 used is a solvent extraction column containing a pulsating device and selected internal tray internals, and other technical devices may be used. The pressure in the column 4 is higher than the pressure of the vapor pressure of the contained mixture to avoid boiling of the mixture.

The water used in unit 4 is derived from stream 3 and a supplementary stream 22 of water. When water is recovered from stream 3 to stream 9, the mass flow ratio of stream 3 to stream 9 is greater than 30. The solvent injection rate of unit 4 needs to be greater than 6 to extract the percentage of phenol and tar acid in the oil feed. The aqueous solvent removes more than 95% of the phenol and tar acid in the original oil, and the effluent stream 6 contains less than 5% acid.

The stream 5 is then introduced into a liquid-liquid phase extraction unit 8 containing a non-water miscible solvent, which in this example is identical to 4 in this example, has a pulsating device and is injected with a solvent. The logistics flow in counter-flow, and other technology devices can also be used. It is worth noting that the mixing parameters, properties and interior arrangements of the device 8 are different from the device 4.

In column 8, the aqueous stream 5 is combined with a non-water miscible, mono- or polycyclic aromatic hydrocarbon with or without a substituent or a mixture thereof in countercurrent extraction. In this case the solvent is toluene. The pressure in the column 8 is higher than the pressure of the vapor pressure of the contained mixture to avoid boiling of the mixture.

One end of the column 8 is an acid-rich aroma extract 10, and the other end outlet is circulated to a first stage solvent (water) stream 9 for reuse by the first column 4. Since the selected aromatic compound is extremely low in solubility in an aqueous solution, a clearly separated phase can be obtained without the use of other special devices. The toluene entering the column from stream 7 is primarily from the condensation and cooling of hydrocarbons recovered from stream 17 to stream 7 and may be supplemented by stream 23. The water recovered from stream 9 is recovered from stream 3 into column 4, which is substantially free of phenol and tar acid. In this case its content is less than 900 parts per million.

The organic stream 10 recovered from the outlet of the column 8 is preheated to about 120 ° C in a heat exchanger 11 , which corresponds to the temperature at which the mixture is bubbled. The composition of the stream contains less than 10% by weight of phenol and tar acid. .

The preheated mixture 12 is introduced into the distillation column 13. The almost pure secondary solvent is recovered above the distillation column 13, while the lower portion is mainly tar acid, the tar acid contains less than 10% by weight of toluene, and some traces which can be extracted from the raw oil raw materials. Compound. In this example, the distillation column is operated at atmospheric pressure.

The secondary solvent is recovered as overheads 15, which are condensed in a condenser 16 and cooled to the desired temperature, and streams 17 and 7 are passed to column 8 as a recovery solvent.

Finally, the tar acid mixture formed in the distillation sump 14 is introduced into a melt static crystallization unit 19, which is MSC method. Pure phenolic products having a purity greater than 99% can be obtained in stream 20 via crystallization, while other tar acids contained in the initial mixture 14 are recovered in stream 21 with phenol and other trace extractable compounds.

While the invention has been described above in terms of several preferred embodiments, it is not intended to limit the scope of the present invention, and any one of ordinary skill in the art can make any changes without departing from the spirit and scope of the invention. And the scope of the present invention is defined by the scope of the appended claims.

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BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a treatment apparatus for producing a mixture of pure phenol and tar acid from an oil containing phenol and tar acid according to the present invention.

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Claims (9)

A method for producing phenol and tar acid from an oil, comprising the steps of: i) adding an oil to a liquid-liquid phase extraction device in the form of water to extract phenol and tar contained in the oil The acid is an aqueous solution containing phenol and tar acid and recovers the treated oil; ii) the aqueous solution containing phenol and tar acid is added to a liquid-liquid phase extraction apparatus in the form of a hydrocarbon solvent. The hydrocarbon is composed of a non-water-miscible mono- or polycyclic aromatic hydrocarbon or a mixture thereof to extract the phenol and tar acid from the aqueous phenol-containing solution to obtain an aqueous solution containing a phenol and tar acid and a a phenolic hydrocarbon; iii) distilling the phenol and tar acid-containing hydrocarbon at a pressure lower than, equal to or higher than atmospheric pressure, and purifying and recovering the hydrocarbon as an overhead; iv) The bottom product of the distillation recovers the phenol and tar acid, the phenol and tar acid are a mixture of concentrated phenol and tar acid substantially free of hydrocarbons and water; v) recovering the water lacking phenol and tar acid to Liquid phase-liquid phase extraction device of step i) And vi) recovering the hydrocarbon of step iii) to the liquid-liquid phase extraction apparatus of step ii). The method of claim 1, wherein the hydrocarbon of step ii) consists of a non-water-miscible mono- or polycyclic aromatic hydrocarbon having at least one alkyl group substituted or a mixture thereof. The method of claim 2, wherein the hydrocarbon is selected from the group consisting of: benzene, toluene, o-xylene, m-xylene, p-xylene, 1,3,5-trimethylbenzene, ethylbenzene, 1- Methyl ethylbenzene, 1-ethyl-2 toluene, 1-ethyl-3-tolyl naphthalene, 1,2-dimethyl-3 ethylbenzene, 1,2-dimethyl-4-ethylbenzene, 1,2 - dimethyl-5 ethylbenzene, 1,3-dimethyl-2 ethylbenzene, 1,3-dimethyl-4 ethylbenzene, 1,3-dimethyl-5ethylbenzene, 1,4-two Methyl-2-ethylbenzene, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1-ethylnaphthalene, 2-ethylnaphthalene, 1,2-dimethylnaphthalene, 1,6-dimethylnaphthalene , diphenyl, 2,6-dimethylnaphthalene, anthracene, fluoranthene, phenanthrene, or a mixture thereof. The method of claim 1, further comprising: vii) recovering the tar acid mixture and the pure phenol by at least one melt crystallization of the concentrated phenol and tar acid mixture. The method of claim 1, further comprising: vii) extracting the concentrated phenol and tar acid mixture to combine at least one melt crystallization and at least one distillation to extract a phenol-containing tar acid fractionated compound. The method of claim 5, wherein the purifying of step vii) is by using a combination of two melt crystallizations and one distillation to extract a fractionated compound of phenol-containing tar acid. The method of any one of claims 1 to 6, wherein the liquid-liquid phase extraction of steps i) and ii) is at a pressure between 60 and 160 ° C and higher than the vapor pressure of the internal mixture. Under the operation. The method of any one of claims 1 to 6, wherein the oil is an oil raw material containing phenol and tar acid. The method of any one of claims 1 to 6, wherein the solvent in the form of the hydrocarbon is toluene.